The sisters often found themselves sleeping tangled together, their wings providing the warmth they needed since they didn't use the blankets on the bed. It was like a royal nest of sorts, from the days when they were no more than fillies and the weight of the crowns on their heads was nothing more than a faraway dream. Both mares were fully grown, having been raising and lowering both the sun and the moon for over a thousand years. They'd ruled together in harmony as a perfect Diarchy, and the ponies beneath their reign had flourished within that time frame. Enemies had come and gone, having been defeated in one way or another.
The Kingdom of Equestria stood proud, a unified whole to their subjects. Behind closed doors though, a different story revealed itself. Celestia was not herself anymore, often ranting to people who no longer stood in her presence; long gone to the ravages of time. She would grow violent, attacking staff at random and screeching about the return of Tirek or Sombra. Princess Luna had watched with growing concern, smoothing things over with the palace staff and apologizing profusely to those she'd hurt in some way. Whether physically, emotionally, or mentally, Princess Celestia's outbursts caused harm to the ones she'd claimed to love for millennia.
An outburst earlier tonight had been especially bad, and it had taken the Royal Guard along with Princess Luna to subdue the Solar Regent and sedate her so that she could get some sleep. Normally she was fine during the day, but as the sun slipped towards the horizon she would change. She'd become a stranger to her sister and everyone who knew her, but royal protocol had demanded that they act like nothing was wrong. In the moments where Celestia was lucid she would collapse with sorrow, regret overwhelming her from the things she'd said and done without realizing it. She was losing the battle with her mind, and it was taking its toll on not just her, but everypony around her.
Eventually, in the late hours of the night Princess Luna once again found herself waking up. Moonlight shone through the windows in their personal chambers, illuminating the pair of ponies. Slowly extricating herself from the nest, Luna got out of bed and looked around their room. Knickknacks and memories lie scattered around from when Celestia had been playing the night before, as it seemed to help in some small way. Sometimes in these episodes she seemed like a young foal again, so the toys had been attempts at calming her. It was always better when they had an effect, but when they didn't the nights seemed to last forever.
Moving to the window, Princess Luna looked outside out at the castle grounds. She could see the trees moving in the gentle night breeze, and could almost hear the way the flowers seemed to sigh as they were caressed by the air. Her face was a picture of somberness, as once again she tried to think of a solution. These episodes were only getting worse with time, and all the doctors had agreed there was no cure. Princess Celestia was losing her mind, quite literally. Her memories were stolen inch by inch, and soon it would no longer just be when the sun was going down. Her hostility and fear would infect her, reducing everypony she'd ever known into nothing more than a complete stranger.
It had broken Luna's heart when Celestia didn't recognize her tonight, and it broke again when she realized what she had to do. Not just for the throne, but for the kingdom. It was terrible, it was necessary, and she would have to do it now before dawn arrived and woke her sister up. There was simply no other way, and it would also be a mercy to the Solar Princess. To help her before the rest of her mind was gone, and she wasted away a mere shell of herself, wailing about strangers who were the very people she would scream to for help. Still, it didn't ease the pang in the Lunar Princess' soul as she turned around to look at the bed.
She gritted her teeth, clenching her jaw as she steeled herself. At least it would be quick, she reasoned. As quiet as a mouse she got back onto the bed, using her wings to smooth some mane off of Celestia's cheek. "I'm so sorry, sister," she murmured then. "I love you, and I always will."
The sedative had been a powerful one, and the other mare didn't even so much as stir. She continued breathing deeply and evenly, sleep having taken her away. Princess Luna then kissed her sister's forehead, and gave her the most lovely of dreams. A smile lingered on Celestia's face, the happy memories soothing the strain from her brow, and causing her to relax further into the bed. Tears welled up in Princess Luna's cyan eyes, and she then sucked in a deep breath. Every moment that passed made the sun come closer to the horizon, and she would soon be roused for her daily ritual of raising it so that the ponies could start their day. It was now or never, and Princess Luna chose now.
She lowered her horn, waiting carefully until Celestia shifted in her sleep and exposed her throat. Then without anymore hesitation, she jerked her head from right to left and cut deep. Low sobs fell from her throat as Celestia began to bleed, her life force quickly coating her snow white form and covering the sheets. All too soon, or perhaps not soon enough, enough crimson coated the pair and the bed for there to be no way to save her. Princess Luna remained with her sister until the very end when the powerful heart stopped beating, and she gave her forehead another kiss while she openly wept.
Getting out of bed again, the Lunar Princess cleaned herself off with as many towels as she could find with her magic, then left the room to find the Royal Guard. Informing them that the Solar Princess had passed away, she led a small number of them back into the chambers. It would be immediately obvious to them what their ruler had done, but none of them spoke on it. Instead they cleaned and prepared the body, while Luna did her best to bring herself together from the torrent of tears.
Several hours later, completely serene yet stone faced, the new sole ruler of Equestria went outside to lead the funeral for her best and closest friend, the one who's life she'd secretly taken in order to spare any more pain. The scent of the flowers in the bouquets would haunt her until the end of her very long days, as would the smile on Celestia's face as she'd breathed her last without ever knowing it.
It was the end of the sun, and the beginning of the moon. May God have mercy on her soul.
Author's Note
another song story decided to birth itself on me, this one from a song a lot of us know as "that creepy music box song from criminal minds" that likes to get stuck in my head.
also, serius est quam cogitas is latin for 'it's later than you think' which is a motto from the sundials. totally not ominous, right?
